With the improvement of operation speed of recent electric devices such as data storage devices, the speed of the reading-writing and locating is accelerated accordingly. Thus, more and more heat is generated. In order to maintain the electric devices work normally, the heat generated by the electric devices must be dissipated rapidly. Fans act an important role during the heat dissipation. The design and lifetime of bearings in the fans determine the performance and the life of the fans.
An example of a conventional bearing structure is shown in FIG. 8. The bearing structure comprises a rotary shaft 1a and a stationary bearing 2a which defines a central bore 3a for receiving the shaft 1a. A small gap is formed between the shaft 1a and the bearing 2a for holding lubricating oil therein. However, when the gap is too narrow, the lubricating oil will be extruded out of the gap so that large-area dry friction exists between the shaft 1a and the bearing 2a. This results in the bearing structure wearing out to thereby reduce the lifetime of the bearings structure and generate undesired noise. On the contrary, when the gap is significantly wide, the shaft 1a is prone to sway radially or unsteadily to generate noise as well.
A new bearing structure that overcomes the above-mentioned disadvantages is desired.